A vehicle air-conditioning system mainly includes a compressor, a condenser, a throttling clement, and an evaporator. A gaseous refrigerant with high temperature and high pressure discharged from the compressor changes into a liquid refrigerant after being condensed by the condenser. The liquid refrigerant is throttled and depressurized by the throttling element and then enters into the evaporator to exchange heat in the evaporator, with air outside the evaporator, and changes into the gaseous refrigerant and then flows back into the compressor, thus accomplishing a refrigeration cycle. The air enters into a vehicle compartment after being cooled by the evaporator, and if the temperature in the vehicle compartment is lower or higher than a preset temperature in the vehicle compartment, a superheat degree is controlled by controlling and regulating an opening degree of the throttling element.
Adopting an electronic expansion valve as the throttling element in the above process has advantages as follows.
The electronic expansion valve may be regulated according to various parameters in the air-conditioning system, and the corresponding control strategy is timely adjusted according to various working conditions, thus realizing improving of an efficiency of the refrigerating system, and the energy conservation and environment protection. Controlling the superheat degree by the electronic expansion valve is smoother than controlling the superheat degree by a thermal expansion valve, thus allowing a temperature of air outputted to be stable, and a degree of comfort to be improved.
However, in the conventional technology, when the electronic expansion valve generates a stalling fault and gets stuck somewhere thus cannot be operated, or when a fault occurs to the electronic expansion valve and the electronic expansion valve cannot be opened to a certain interval, the conventional vehicle air-conditioning system cannot take corresponding countermeasures against the fault, which may cause the air-conditioning system to be damaged.